How Science Helps the Warriors Sleep Their Way to Success

For 10 years, Andre Iguodala slept terribly. Back in college, the Golden State Warriors forward would play videogames late into the night. Eventually he'd crash, sometimes as late as 4 am, only to wake up a few hours later for practice. Then came class. When he was lucky, he'd squeeze in an afternoon nap. Later that night, it'd be back to videogames—either that or Fresh Prince reruns.

Iguodala's brutal sleep habits followed him to the NBA. Only in 2013, after joining the Warriors, did he manage to connect with Cheri Mah, a physician scientist at the UC San Francisco's Human Performance Center.

"Sleep duration is important, but we also focused on the quality and timing of Andre's sleep," says Mah, who consults with teams in the NFL, MLB, NHL, and NBA—including the Warriors—on sleep and recovery strategies. "We worked on his caffeine intake, his nutrition, his wind-down routine. Big picture, we worked on his whole approach to sleep, to make it more of a priority."

Did it work? Sample size of one and all that, but boy, did it ever seem to: With more sleep, Iguodala's three-point-shot percentage doubled. His points-per-minute spiked 29 percent. His turnover and foul rates fell 37 and 45 percent, respectively. His coaches gave him more game time, and, in the 2015 Finals, tasked him with guarding Cleveland Cavaliers powerhouse LeBron James. The Warriors went on to win the series. Iguodala received the Most Valuable Player award.

Mah, who has been studying the relationship between sleep and performance in elite athletes for more than a decade, is modest about her role in Iguodala's rise to MVP status. She's cagey, too, about her work with individual players and teams. She declines to discuss, for example, Iguodala's recovery strategy these past few weeks. When a knee injury sidelined him during the Western Conference finals last month, some speculated that Iguodala would sit our the remainder of the playoffs. But in Wednesday's Game 3 NBA finals matchup against Cleveland, he was back—a bit slower than usual, but not too slow to make things difficult for James, or to drive for a dunk in the game's final minutes to give the Warriors a three-point lead.

So was it sleep that brought Iguodala back, or something else?

Realistically, it was probably some combination of nutrition, physical therapy, and rest. But to hear other athletes tell it, sleep makes for especially strong medicine. Two weeks ago, when reporters asked James how he planned to prepare for Game 7 of the Eastern Conference finals, he said: "Try to get as much sleep as I can … that's the best recovery that you can possibly get." (This from a man who reportedly spends some $1.5 million a year on training, diet, and physical therapy.)

Mah puts it in even starker terms: "The comparison most of us make, when talking about the importance of sleep, is to performance-enhancing drugs," she says. "All these athletes are looking for that extra 1 percent boost in performance. But when you look at the research, it suggests a solid foundation of rest and recovery is worth way more than 1 percent."

How much more? In a seminal study from 2011, Mah got members of Stanford's men's basketball team to up their nightly sleep sessions by an average of 110 minutes. After five to seven weeks, Mah found the extra shut-eye correlated with a 9 percent boost in both their free-throw and three-point accuracy and a 0.7-second improvement on a grueling 282-foot sprint drill. She was shocked, and the athletes were, too. "These aren't amateurs—a 9 percent improvement isn't the kind of thing you typically see in players at this level," she says.

If sleep could make that big a difference for individual athletes, just imagine what it could do for an entire team. "A lot of organizations don't strategize over things like travel and practice schedules," Mah says. What time does your flight leave? What direction will you be traveling? How many time zones will you cross? How long will you be away? These are just some of the factors she considers when helping teams develop a comprehensive sleep program.

"I'll talk to NFL teams and say, why do you always travel at 2 pm on a Friday, whether you're traveling from east to west or west to east? And they'll say, well, that's just what we've always done,” Mah says. “They'll fly to wherever they're going and just hope their bodies adjust."

Bad idea. Evidence suggests athletes perform their best in the late afternoon. Not late afternoon local time, but late afternoon as defined by one's biological clock; to the body of an American athlete in Paris, a competition at 7 pm can feel like it's happening at 11 in the morning. By that logic, you might expect a West Coast team to have a circadian edge over an East Coast team during, say, a night game. Indeed, when Mah and her colleagues looked at 40 seasons' worth of NFL data, they found that West Coast teams experienced a consistent advantage over Atlantic competitors during evening match-ups.

Results like these are why Mah advises teams to take a more proactive approach to travel planning. "The rule of thumb is it takes one day per hour of time-zone change to adjust to a new schedule, so a team traveling coast-to-coast will take three days to acclimate," she says. Depending on how long they'll be away, Mah says, teams can begin shifting their body clocks in advance by going to bed earlier, waking up earlier, and using bright-light exposure to shift their circadian clocks. She'll also advise them on when to seek or avoid light once they arrive at their destination, when to schedule their walk-throughs and team meetings, and when to schedule their return flights in relation to their games.

And people actually stick to these schedules? Again, Mah declines to comment on the sleep hygiene of specific teams and players. In general, though, she says every team would benefit from more and higher-quality shut-eye—and her research continues to point to sleep's essential role in peak performance.

In 2016, ESPN recruited Mah to assist with its Schedule Alert project. The goal was to try to predict when NBA teams would lose, based solely on their schedules: How many time zones had they traveled to compete? How much time had they had to recover since their last game? Mah and her collaborators used a formula to identify 42 games throughout the 2016–17 season in which teams would be susceptible to fatigue. They predicted the outcome of 29 of them. This past season, they correctly picked 42 games of 54.

"Our hope with that project was to highlight that these schedule-related factors, and their effect on sleep and recovery, could be affecting game outcomes," Mah says. "I'd like to think we've helped advance the conversation around rest, travel, and performance."

By the looks of things, the league is listening. NBA commissioner Adam Silver recently called player rest and health the NBA's single biggest issue. This past year, the league extended the season by a week to eliminate instances of teams playing four games in five days and to reduce each team's number of back-to-back games from 16 to 14.

One perk of the NBA's Finals schedule is the way it controls for playing conditions. With the exception of Game 1 (which the Cavaliers entered on four days' rest; the Warriors three), the two teams have had the same time to recover between match-ups and traveled the same distance. Any variability in players' readiness will be down to other factors. The Warriors will have Iguodala (all signs point to him being healthy and ready for Game 4), but the greatest advantage Friday might belong to the Cavaliers. Not only will they be playing on their home court—they'll have spent the last few nights in their own homes, sleeping soundly, Cleveland fans should hope, in their own beds.

Robbie Gonzalez is a senior writer at WIRED, covering humanity’s evolving relationship with science and technology. He was previously the editor of WIRED’s design desk. Prior to joining WIRED he was the senior science editor of Gizmodo. Before that, he was a reporter at io9. Gonzalez holds bachelor’s degrees in... Read more

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